Computer-aided design software can be used to construct and manipulate computer drawings of objects referred to as "models". The user is presented with a display of the model on the computer screen and manipulates the model using keyboard commands, a mouse/cursor combination, and other various input means. Changes to the model are reflected in the screen display of the model as the user makes the changes or, alternatively, in response to the user issuing a specific command to update the screen display of the model. In either case, the screen display of the model serves as the main source of model information to the user and as the user's reference for inputting and changing features of the model.
As modeling software becomes more powerful, it also becomes more complex. This increase in complexity increases the difficulty of use of the modeling software. If the software becomes too complex, then the user will have a difficult time making modifications and/or determining critical information about the model, especially since the screen display of the model is the user's main source of information and point of reference for facilitating input. This problem becomes more acute when the model is a three-dimensional model since, depending on the modeling software and the nature of the model, it is sometimes difficult, if not impossible, to see the entirety of the model at any one time.
One way to address the increasing complexity of modeling software is to provide alternatives to the traditional techniques for presenting the model information to the user that allow the user to manipulate the model information. U.S. Pat. No. 5,006,991 to Ohcoshi et al. discloses a system for graphically checking interference between stationary and moving objects. A design layout is graphically displayed and an object or a person is moved through the design layout by the graphical display device. Column 9, lines 64-66 indicate that along with displaying the design layout, the system can display a chart showing connections and positions of objects in the design layout.
Although the Ohcoshi et al. patent addresses a specific problem associated with modeling in the specific situation discussed in the patent, it does not address the general problem of modeling software complexity and unwieldiness and it does not provide a general alternative technique for accessing and manipulating models. Accordingly, it is desirable to provide an alternative and effective technique for presenting and manipulating model data that allows the user to easily make changes to a model and that presents model information to the user that is useful although not apparent from simply viewing the model on the screen display.
Certain industries present particular modeling problems. For example, manufacturers of sheet metal parts may wish to model certain features that are formed in sheet metal, such as louvers, lances, ribs and the like. A company known as PTC has a forming tool that can be used to assist in modeling form features of sheet metal parts. However, known forming tools have significant drawbacks. In particular, known forming tools in computer-aided modeling systems typically do not permit storing of significant modeling information, such as an orientation sketch, the surfaces to be removed, stopping surfaces, and the like. Thus, this and other information must be specified every time the tool is used. Also, known tools do not dynamically preview the result that will occur if the forming tool is used on a particular model part. Therefore, a need exists for a forming tool function in a software modeling system that permits convenient use and reuse and for a forming tool function that dynamically previews the result that will occur upon use of the tool.